JPWO2019026351A1 - Electric power steering device - Google Patents

Abstract

Provided is a high-performance electric power steering device capable of smoothly switching steering with a simple configuration when a driver steers a steering wheel during automatic steering control, so that the driver does not feel uncomfortable. . SOLUTION: A manual steering control for driving a motor by a first motor current command value calculated based on at least a steering torque and a steering angle control unit are calculated so that an actual steering angle follows a target steering angle. In the electric power steering apparatus having a function of switching between automatic steering control for driving the motor according to the second motor current command value, calculation processing is performed on the steering torque in accordance with the steering state and the vehicle speed to correct the target steering angle. A target steering angle correction unit that outputs a value; and a correction output unit that corrects the target steering angle with a target steering angle correction value and inputs the corrected target steering angle to the control unit. [Selection] Figure 6

Description

  The present invention has a switching function between an automatic steering control mode (steering angle control mode such as parking assistance) and a manual steering control mode (assist control mode) in steering control of a vehicle, and drives a motor by a motor current command value. The present invention relates to an electric power steering apparatus that applies an assist force to a steering system of a vehicle. In particular, the target steering angle value of the steering angle control in the automatic steering control mode is corrected in the same direction as the direction in which the steering torque is applied. The present invention relates to an electric power steering apparatus that improves a driver's steering feeling in a state where a steering torque does not reach a switching threshold by changing an amount according to a vehicle speed and a steering state.

  An electric power steering device (EPS) that applies a steering assist force (assist force) to a steering mechanism of a vehicle by a rotational force of a motor is provided with a steering shaft by a transmission mechanism such as a gear or a belt via a speed reducer. Alternatively, a steering assist force is applied to the rack shaft. Such a conventional electric power steering apparatus performs feedback control of the motor current in order to accurately generate the torque of the steering assist force. In feedback control, the motor applied voltage is adjusted so that the difference between the steering assist command value (current command value) and the motor current detection value is small. The adjustment of the motor applied voltage is generally performed by PWM (pulse width). This is done by adjusting the duty of modulation) control.

  The general configuration of an electric power steering apparatus will be described with reference to FIG. 1. A column shaft (steering shaft, handle shaft) 2 of a handle (steering wheel) 1 is a reduction gear 3, universal joints 4a and 4b, a rack and pinion mechanism. 5, via tie rods 6a and 6b, and further connected to steered wheels 8L and 8R via hub units 7a and 7b. Further, the column shaft 2 is provided with a steering angle sensor 14 for detecting the steering angle θr of the handle 1 and a torque sensor 10 for detecting the steering torque Th, and a motor 20 for assisting the steering force of the handle 1 is a reduction gear. 3 is connected to the column shaft 2 through 3. The control unit (ECU) 30 that controls the electric power steering device is supplied with electric power from the battery 13 and also receives an ignition key signal IG via the ignition key 11. The control unit 30 calculates a current command value for assist control based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12, and a voltage obtained by compensating the current command value. The current supplied to the motor 20 is controlled by the control command value Vref. The steering angle θr is detected from the rudder angle sensor 14 but can also be obtained from a rotation sensor connected to the motor 20.

  The control unit 30 is connected to a CAN (Controller Area Network) 40 that transmits and receives various types of vehicle information, and the vehicle speed Vs can also be received from the CAN 40. The control unit 30 can be connected to a non-CAN 41 that exchanges communications, analog / digital signals, radio waves, and the like other than the CAN 40.

  The control unit 30 is mainly composed of a CPU (including MPU and MCU), and general functions executed by programs in the CPU are as shown in FIG.

  The function and operation of the control unit 30 will be described with reference to FIG. 2. The steering torque Th detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12 (or from the CAN) are expressed as a current command value Iref1. The current command value calculation unit 31 to be calculated is input. The current command value calculation unit 31 calculates a current command value Iref1, which is a control target value of the current supplied to the motor 20, using an assist map or the like based on the input steering torque Th and vehicle speed Vs. The current command value Iref1 is input to the current limiting unit 33 through the adding unit 32A, and the current command value Iref3 whose maximum current is limited by the overheat protection condition is input to the subtracting unit 32B, and the motor current value Im being fed back The deviation Iref4 (= Iref3-Im) is calculated, and the deviation Iref4 is input to the PI control unit 35 for improving the characteristics of the steering operation. The voltage control command value Vref whose characteristics are improved by the PI control unit 35 is input to the PWM control unit 36, and the motor 20 is PWM driven via an inverter 37 as a drive unit. The current value Im of the motor 20 is detected by the motor current detector 38 and fed back to the subtraction unit 32B.

  Further, a rotation sensor 21 such as a resolver is connected to the motor 20, and the actual steering angle θs is detected. The adder 32A is added with the compensation signal CM from the compensator 34, and the compensation of the system system is performed by adding the compensation signal CM so as to improve the convergence and inertia characteristics. The compensator 34 adds the self-aligning torque (SAT) 343 and the inertia 342 by the adder 344, further adds the convergence 341 to the addition result by the adder 345, and the addition result of the adder 345 is the compensation signal CM. It is said.

  In such an electric power steering apparatus, in recent years, vehicles that have an automatic steering control mode (steering angle control mode such as parking assistance) and a manual steering control mode (assist control mode) and have a function of switching between these control modes have appeared. In order to realize automatic steering, a configuration in which the steering angle control and the assist control are independently held and these outputs are switched is common. For steering angle control, position / speed control with excellent performance in response and disturbance suppression is used. Position control is composed of P (proportional) control, speed control is composed of PI (proportional integral) control, etc. .

  A general electric power steering apparatus having functions of a steering angle control mode and an assist control mode and having a function of switching the steering control mode will be described with reference to FIG. 3. A resolver for detecting a motor rotation angle θs is included in the motor 150. A rotation sensor 151 is connected, and the motor 150 is driven and controlled via the vehicle ECU 130 and the EPS ECU 140. The vehicle-side ECU 130 is configured to output a switching command unit 131 that outputs a switching command SW for the steering angle control mode or the assist control mode based on a button, a switch, or the like indicating the driver's intention, and a signal such as a camera (image) or a laser radar. And a target steering angle generator 132 that generates a target steering angle θt based on the above. The actual steering angle θr detected by the steering angle sensor 14 provided on the column shaft (steering shaft, steering wheel shaft) is input to the steering angle control unit 200 in the EPS side ECU 140 via the ECU 130.

  The switching command unit 131 receives a signal for identifying that the steering angle control mode is entered, for example, a vehicle state signal by a button or a switch provided on the dashboard or around the steering wheel, or a parking mode provided for a shift. Based on this, the switching command SW is output, and the switching command SW is input to the switching unit 142 in the EPS side ECU 140. The target steering angle generation unit 132 generates a target steering angle θt by a known method based on data such as a camera (image) and a laser radar, and the generated target steering angle θt is a steering angle in the EPS-side ECU 140. Input to the control unit 200.

  The EPS-side ECU 140 outputs an assist control command value Itref calculated based on the steering torque Th and the vehicle speed Vs, and the steering angle control based on the target steering angle θt, the actual steering angle θr, and the motor angular speed ωr. From the steering angle control unit 200 that calculates and outputs the steering angle control command value Imref for switching, the switching unit 142 that switches the assist control command value Itref and the steering angle control command value Imref by the switching command SW, and the switching unit 142 Based on the motor current command value Iref (= Itref or Imref), a current control / drive unit 143 that drives and controls the motor 150, a motor speed based on the motor rotation angle θs from the rotation sensor 151, a motor speed and a gear ratio And a motor angular speed calculation unit 144 that calculates the actual steering angular speed ωr. The motor angular velocity calculation unit 144 includes a low-pass filter (LPF) for cutting high-frequency noise after the calculation equivalent to differentiation.

  As shown in FIG. 4, the steering angle control unit 200 outputs a steering angular velocity command value ωc so that the actual steering angle θr follows the target steering angle θt, and the steering angular velocity command value ωc. The speed control unit 220 outputs a steering angle control command value Imref so as to follow ωr. Further, the switching unit 142 is based on a switching command SW from the switching command unit 131 of the vehicle-side ECU 130, and an assist control mode (manual steering control) by the assist control unit 141 and a steering angle control mode (by the steering angle control unit 200). Position / speed control mode), the assist control command value Itref is output in the assist control, and the steering angle control command value Imref is output in the steering angle control.

  In the electric power steering apparatus having such a function, conventionally, the back parking and the parallel parking are automatically performed by controlling the actuator (motor) based on the relationship between the movement distance of the vehicle and the turning angle stored in advance. To do. The conventional steering control device calculates the motor current command value so that the actual steering angle coincides with the target steering angle set according to the vehicle, thereby realizing automatic steering control. For example, in the automatic steering device disclosed in Japanese Patent No. 4057955 (Patent Document 1), when switching from rudder angle control to torque assist control, the fade switching time is changed according to the amount of assist torque, thereby switching control. It reduces the sense of discomfort at times.

Japanese Patent No. 4057955 JP-A-2015-93569

  If the driver determines that the steering wheel has been steered during automatic steering control of an electric power steering device that performs automatic steering that causes the actual steering angle to follow the target steering angle, the automatic control is stopped, and assist control for manual steering control is performed. It is desirable to switch smoothly. Even during the steering angle control, if the threshold for determining that the driver has steered has not been reached, it is desirable to continue the steering angle control so that the driver does not feel uncomfortable with the steering operation. Further, if the threshold for determining that the driver has steered has not been reached even during the steering angle control, it is desirable to continue the control with no sense of incongruity with respect to the steering operation of the driver.

  In automatic steering control, control is performed so that the actual steering angle coincides with the target steering angle. However, if the driver applies steering torque by operating the steering mechanism, the actual steering angle deviates from the target steering angle. . Therefore, the automatic steering control outputs a motor current command value in a direction opposite to the steering torque so as to oppose the steering torque so that the actual steering angle matches the target steering angle.

  On the other hand, since the assist control outputs so as to assist the steering torque, it outputs a motor current command value in the same direction as the steering torque. Therefore, when switching from automatic steering control to manual steering control when a steering torque is applied, the respective outputs are in opposite directions, so that the driver temporarily applies automatic steering control after the steering torque is applied. After the assist in the direction opposite to the steering torque is made, the manual steering control is gradually switched by the fade process. That is, the assist in the same direction as the steering torque is finally made. This makes the driver feel that he / she is caught when switching from automatic steering control to manual steering control. Further, in steering at a threshold value or less that does not switch to assist control, the driver cannot steer freely because the output of the steering angle control attempts to match the target steering angle against the driver's steering.

  Japanese Patent Application Laid-Open No. 2015-93569 (Patent Document 2) combines the steering angle deviation and the physical values of the target steering torque and the deviation of the steering torque, and mixes while changing the ratio according to the steering intervention. A steering control device that reflects a driver's steering intervention in a target value so as to reduce the deviation is disclosed. Patent Document 2 reflects the driver's steering intervention in the target value. However, since the weight is set for the assist deviation and the tracking deviation, and the units are matched and mixed according to the weight, the control system becomes complicated. End up. Furthermore, since it is not the structure which considered the driver's dynamic steering, it is difficult to set a dynamic steering characteristic.

  The present invention has been made under the circumstances described above, and an object of the present invention is to smoothly switch the steering with a simple configuration when the driver steers the steering wheel during automatic steering control. The object is to provide a high-performance electric power steering device which does not give a sense of incongruity.

  In the present invention, a manual steering control for driving a motor by a first motor current command value calculated based on at least a steering torque and a steering angle control unit are calculated so that the actual steering angle follows the target steering angle. In addition, the present invention relates to an electric power steering apparatus having a function of switching between automatic steering control for driving the motor according to a second motor current command value, and the object of the present invention is based on the steering state and the vehicle speed. A target steering angle correction unit that performs arithmetic processing and outputs a target steering angle correction value, corrects the target steering angle with the target steering angle correction value, and inputs the corrected target steering angle to the steering angle control unit This is achieved by providing a correction output unit.

  The object of the present invention is that the target steering angle correction unit performs phase advance compensation or phase delay compensation on the steering torque based on the steering state, and first compensation steering torque from the phase compensation unit. And a second compensation steering torque that has a dead zone in a region where the first compensation steering torque is small and increases in the same direction as the first compensation steering torque increase method according to the vehicle speed is output. Or a limiter that limits the upper and lower limit values of the second compensation steering torque in accordance with the vehicle speed and outputs the corrected target steering angle, or of the dead band gain unit. The second phase compensation unit is provided in the subsequent stage, or the target steering angle correction unit inputs the steering torque and has a dead zone in a region where the steering torque is small. A dead zone gain unit that outputs a first compensation steering torque that increases in the same direction as the steering torque increase method according to the vehicle speed, and a phase advance compensation based on the steering state. A phase compensation unit that compensates for phase lag, and a limiter that limits the upper and lower limits of the second compensation steering torque from the phase compensation unit according to the vehicle speed and outputs the corrected target steering angle. Or by providing a second phase compensation unit before the dead zone gain unit, or by reducing the output gain of the dead zone gain unit as the vehicle speed increases, or by limiting the limiter. The value decreases as the vehicle speed increases, or the dead zone is variable according to the vehicle speed, or The rudder state is an increase or a return of the steering wheel, or the determination of the increase and the return is determined based on the relationship between the actual steering angle and the motor angular velocity, or the relationship between the actual steering angle and the steering angular velocity. Or the relationship between the steering torque and the steering angular velocity, the relationship between the steering angular velocity and the deviation of the target steering angle and the actual steering angle, or the rate of change of the target steering angle and the deviation of the steering angular velocity and the target steering angle. This is achieved more effectively by being based on the relationship with the steering angle deviation or by the correction output unit being an addition unit.

  According to the electric power steering apparatus of the present invention, steering angle control of the steering wheel is performed during automatic steering control such as parking assistance and automatic driving. When the steering torque is applied by the driver, the steering torque is added to the target steering angle. The steering angle is controlled so as to match the target steering angle, and the correction amount is varied according to the vehicle speed and the steering state. Thus, when the steering angle control with respect to the corrected target steering angle and the output of the assist control by the steering torque are added at a certain ratio, the directions of the outputs of the automatic steering control and the manual steering control are matched. And the mutual control outputs are less likely to interfere with each other, so that it is possible to reduce a sense of discomfort to the driver that occurs at the time of switching. Further, it is possible to improve the steering feeling when the steering torque does not reach the switching threshold value, which leads to an improvement in safety for the driver.

  In the present invention, since the abrupt target steering angle is controlled in a smooth manner, the driver does not feel uneasy even in automatic driving.

It is a lineblock diagram showing an outline of an electric power steering device. It is a block diagram which shows the structural example of the control system of an electric power steering apparatus. It is a block diagram which shows an example of the electric power steering apparatus which has the switching function of automatic steering control mode and manual steering control mode. It is a block diagram which shows the structural example of a steering angle control part. It is a block diagram which shows the structural example of this invention. It is a block diagram which shows the structural example (1st Embodiment) of the target steering angle correction | amendment part of this invention. It is a characteristic view which shows the example of a characteristic of a dead zone gain part. It is a characteristic view which shows the example of a characteristic of a limiter. It is a characteristic view for demonstrating phase compensation. It is a diagram which shows the example of determination of a steering state (addition / switchback). It is a block diagram which shows the structural example of a steering angle control part. It is a block diagram which shows the structural example of a rate limiter. It is a characteristic view which shows the example of a characteristic of a rate limit value. It is a flowchart which shows the example of whole operation | movement of this invention. It is a flowchart which shows the operation example of a target steering angle correction | amendment part. It is a block diagram which shows the structural example (2nd Embodiment) of the target steering angle correction | amendment part of this invention. It is a block diagram which shows the other structural example (3rd Embodiment, 4th Embodiment) of the target steering angle correction | amendment part of this invention.

  In the present invention, when the steering torque is applied from the driver, the target steering angle is corrected to the same direction as the direction in which the steering torque is applied, and the steering angle control is performed so as to coincide with the target steering angle. In addition, by changing the correction amount of the correction unit according to the vehicle speed, it is possible to appropriately set the correction amount according to a change in vehicle characteristics due to the vehicle speed. The inclination (gain) of the correction amount with respect to the torque is set so as to decrease as the vehicle speed increases, and the correction amount of the correction unit is limited by a limit value that decreases as the vehicle speed increases so that it is not corrected excessively. .

  In addition to this, in the present invention, a phase compensation unit is provided either before or after the gain unit having a dead zone, and the phase compensation characteristic is changed between when the steering wheel is turned back and when the characteristic of the phase compensation unit is increased. Thereby, the driver can deflect the vehicle within the range of the correction amount limit value when the driver is steering within the range where the steering angle control is not stopped. The limiter is provided to prevent excessive vehicle deflection by the driver during automatic driving. In addition, when switching from rudder angle control to assist control, the rudder angle control with respect to the corrected target steering angle and the output of assist control by the steering torque are added and controlled at a certain ratio. The output directions of the angle control and the assist control can be made coincident with each other, so that the mutual control outputs hardly interfere with each other, and the uncomfortable feeling to the driver that occurs at the time of switching can be reduced.

  In addition, by switching the characteristics of the phase compensation unit between the switchback and the switchover, a difference in the correction amount occurs between the switchover and the switchback, so that the steering torque hysteresis can be varied. The dynamic steering characteristic can be adjusted by changing the phase compensation characteristic. For example, if the phase lag is set at the time of increase, the correction amount is delayed with respect to the change of the steering torque, so the steering torque increases during the increase, so that the hysteresis can be widened, and the phase lag of the phase compensator is large. In this case, since the correction amount due to the steering torque is delayed, the steering torque becomes larger than when the phase delay is small. For example, when increasing the hysteresis, the phase width at the time of addition is set to a phase lag compared to that at the time of switching back, so that the hysteresis width at the time of steering is wider than when the characteristics of the phase compensation unit are not switched. It can be provided. By adding hysteresis, the steering feeling can be adjusted, and there is an advantage that it does not react excessively to a torque change caused by a disturbance from the road surface or a change in the steering angle control amount.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 5 shows an embodiment of the present invention corresponding to FIG. 3, and the steering torque Th from the torque sensor 154 depends on the steering state ST and the vehicle speed Vs from the increase / return determination unit 160. A target steering angle correction unit 230 that performs arithmetic processing and outputs the calculated target steering angle correction value θha is provided. The target steering angle θt is added to the target steering angle correction value θha from the target steering angle correction unit 230 by an addition unit 145. Added and corrected. The corrected target steering angle θto corrected by the adding unit 145 is input to the steering angle control unit 200. The steering angle control unit 200 inputs the actual steering angle θr and the motor angular velocity ω, and outputs the calculated motor current command value Imref. .

  The target steering angle correction unit 230 has the configuration shown in FIG. 6 (first embodiment). From the phase compensation unit 231 that compensates the phase advance compensation or phase delay based on the steering state ST, and the phase compensation unit 231. 7, and a dead zone DB having a dead zone DB in a region where the compensated steering torque Th 1 is small as shown in FIG. 7 and outputting a compensated steering torque Th 2 that increases in the same direction as the method of increasing the compensated steering torque Th 1. The gain unit 232 and a limiter 233 that limits the upper and lower limit values of the compensation steering torque Th2 and outputs the target steering angle correction value θha.

  The vehicle speed Vs is input to the dead zone gain unit 232, and as shown in FIG. 7A, the compensation steering torque Th2 having a constant dead zone DB and changing linearly is outputted, and the output gain (tilt) is It decreases as the vehicle speed Vs increases. That is, from the dead zone gain unit 232, the higher the vehicle speed Vs, the smaller the compensated steering torque Th2 and the dead zone DB. FIG. 7A shows an example in which the dead zone DB is constant and the output gain (tilt) is linear, but as shown in FIG. 7B, even if the dead zone DB is varied according to the vehicle speed Vs. good. That is, as the vehicle speed Vs increases, the dead zone DB also increases as DB1 → DB2 → DB3. Further, in FIGS. 7A and 7B, the output gain increases linearly, but may be non-linearly increased as shown in FIG. 7C. Although the dead zone (DB4 to DB6) is variable according to the vehicle speed Vs in FIG. 7C, it may be constant.

  Further, the vehicle speed Vs is also inputted to the limiter 233, and the limit value becomes smaller as the vehicle speed Vs becomes higher as shown in FIG. That is, in the limiter 233, the upper and lower limit values are limited by a smaller limit value as the vehicle speed Vs is higher.

  By switching the characteristics of the phase compensation unit 231 between the steering state ST at the time of switching back and increasing, a difference is generated in the correction amount at the time of increasing and switching back, so that the hysteresis of the steering torque Th can be varied. It becomes. FIG. 9 shows the characteristics in the case of no phase compensation (solid line characteristic B), in the case of phase lag compensation (dashed line characteristic C), and in the case of phase advance (dotted line characteristic D). When the phase lag is large, the correction amount is delayed with respect to the change in the steering torque Th. Therefore, the steering torque is larger than when the phase lag is small. During automatic steering, when the driver steers and the torque increases, the steering wheel tries to return to the target steering angle θt, and the relationship between the steering angle θ and the steering torque Th is as shown by the characteristic A in FIG. If a logic for correcting the target steering angle θt according to the torque is inserted, the relationship between the steering angle θ and the steering torque Th can be changed as shown in the characteristic B. In the case of phase advance, the correction starts earlier, so that the characteristic D is obtained. In the case of phase delay, the correction is delayed, and thus the characteristic C is obtained.

  The steering state ST input to the phase compensation unit 231 is determined by the increase / failback determination unit 160. For example, as shown in FIG. 10, the increase / switchback determination unit 160 determines that the sign of the steering angle θ and the motor angular velocity ω coincides with the increase, and determines that the sign is different as the switchback. Yes. The determination of increase / return may be performed by a combination of the following signals. In any case, the case where the signs match is increased, and the case where they do not match is determined as return. The relationship between the actual steering angle and the motor angular velocity, the relationship between the actual steering angle and the steering angular velocity, or the determination based on the steering torque and the steering angular velocity, the determination based on the steering angular velocity and the deviation of the target steering angle and the actual steering angle before correction, For example, there is a determination based on the deviation of the target steering angle before the correction and the deviation of the steering angular velocity and the deviation of the target steering angle and the steering angle before the correction.

Target steering angle correction unit 230 in the corrected target steering angle correction value? Ha is input to the adder 145 as a correction output unit, corrects the target steering angle θto which corrects the target steering angle [theta] t by an adder 145 (= θt + θha) Is input to the rudder angle control unit 200, and the rudder angle control unit 200 calculates and outputs the motor current command value Imref.

  FIG. 11 shows a configuration example of the rudder angle control unit 200, and smoothing when the corrected target steering angle θt0 from the adding unit 145 changes suddenly, that is, smoothly changing within a predetermined time change rate range. The corrected target steering angle θt0 is input to the rate limiter 211, and the target steering angle θta that has passed through the LPF 212 that removes high-frequency disturbances is input to the subtraction unit 213A. The actual steering angle θr is subtracted and input to the subtraction unit 213A, and the angular deviation from the smoothed target steering angle θta is multiplied by the gain Kpp by the proportional gain (Kpp) unit 214 and added to the subtraction unit 213B as the motor speed command value ωe. Entered. The motor angular velocity ω is subtracted and input from the motor angular velocity calculating unit 144 to the subtracting unit 213B, and the calculated speed deviation Df is multiplied by the gain Kvi by the integrating gain (Kvi) unit 216B via the integrating unit 216A and added to the subtracting unit 213C. At the same time, the speed deviation Df is multiplied by the gain Kvp by the proportional gain (Kvp) unit 216C and is subtracted and input to the subtraction unit 213C. The motor current command value Ib, which is the result of subtraction in the subtraction unit 213C, is output as a motor current command value Imref via a limiter 217 that limits the upper and lower limit values.

The rate limiter 211 smoothes and outputs when the corrected target steering angle θt0 changes abruptly, and has a configuration as shown in FIG. 12, for example. That is, the corrected target steering angle θt0 is added to the subtraction unit 211-1, and the steering angle θt1 as a result of subtraction from the past value from the holding unit (Z ⁻¹ ) 211-4 is input to the change setting unit 211-2. Entered. The change setting unit 211-2 performs upper and lower limit processing on the steering angle θt1, and outputs the change to the adder 211-3 as the change θt2. The adder 211-3 outputs the addition result of the change θt2 and the past value as a new target steering angle θt3. The change amount setting unit 211-2 restricts the change amount so as not to exceed the set upper limit and lower limit. The processing executed at each calculation cycle T is to obtain a difference between the input (target steering angle) θt0 and the target steering angle θt3 of the previous calculation cycle, and when the change is outside the upper and lower limits of the change setting unit 211-2. Is performed by repeatedly adding the difference θt2 limited by the upper limit or the lower limit to the past value. An example of the result obtained by this processing is shown in FIG. The upper limit is S, and even if there is a step-like input (target steering angle) θt0 of size 4S, the output θt3 is changed in a stepwise manner of size S, and finally the output θt3 is changed to the target steering angle θt0. To match. When the difference from the input (target steering angle) θt0 is within the upper and lower limits of the change setting unit 211-2, the change θt2 = the difference θt1 is output and added to the past value. The result output θt3 matches the input (target steering angle) θt0. FIG. 13 corresponds to the case where the upper limit is set to 4S or more. As a result, even if the target steering angle θt0 changes abruptly, the target steering angle θt0 that changes abruptly can be changed smoothly, preventing sudden current changes (= rapid steering) and It plays a function to reduce the anxiety of autonomous driving.

  An example of the overall operation in such a configuration will be described with reference to the flowchart of FIG.

  When the operation of the steering system starts, torque control by the torque control unit 141 is performed (step S1), and the motor 150 is driven by the current control / drive unit 143 using the motor current command value Itref (step S2). The above operation is repeated until a switching command SW is output from the switching command unit 131 (step S3).

  When the steering command SW is output from the switching command unit 131, the steering torque Th is input (step S4), and the steering state ST is determined by the increase / switchback determination unit 160 (step S5). The vehicle speed Vs is input (step S6), and the target steering angle correction unit 230 calculates the target steering angle correction value θha (step S10).

  Further, the target steering angle θt is input from the target steering angle generation unit 132 (step S20), and is corrected by adding the target steering angle correction value θha to the target steering angle θt by the adding unit 145 (step S21). The corrected target steering angle θto is input to the steering angle control unit 200 (step S22). In addition, the actual steering angle θr is input from the steering angle sensor 152 (step S23), the motor angular speed ω is input from the motor angular speed calculation unit 144 (step S24), and the motor current command value Imref is generated by the steering angle control unit 200. (Step S25). Thereafter, the switching unit 142 is switched by the switching command SW from the switching command unit 131 (step S26), and the motor 150 is driven by the current control / drive unit 143 using the motor current command value Imref from the steering angle control unit 200. (Step S27), the process returns to Step S3. The drive control based on the motor current command value Imref is repeated until the switching command SW is changed from the switching command unit 131.

  Next, an operation example (step S10 in FIG. 14) of the target steering angle correction unit 230 will be described with reference to the flowchart in FIG.

  The phase compensation unit 231 compensates the steering torque Th based on the steering state ST for phase advance compensation or phase lag compensation (step S11), and the compensated steering torque Th1 from the phase compensation unit 231 is input to the dead band gain unit 232 and the vehicle speed Vs. Is multiplied by the gain (step S12). The compensation steering torque Th2 from the dead band gain unit 232 is input to the limiter 233, and the upper and lower limits of the compensation steering torque Th2 are limited by a limit value corresponding to the vehicle speed Vs (step S13), and the target steering is limited to the upper and lower limits. The angle correction value θha is output (step S14).

  In the target steering angle correction unit 230 of FIG. 6, the phase-compensated compensation steering torque Th1 is input to the dead band gain unit 232 and multiplied by the gain, but the steering torque Th is input to the dead band gain unit 232 as shown in FIG. After the input and gain multiplication, the phase compensation unit 231 may perform phase compensation (second embodiment). Further, as shown in FIG. 17A, a second phase compensation unit 231A may be provided after the dead band gain unit 232 of the first embodiment shown in FIG. 6 (third embodiment). In this case, one of the two phase compensators 231 and 231A can be mainly used for target correction, and the other can be used for noise removal or the like, and a smoother feeling can be obtained. Further, as shown in FIG. 17 (B), a second phase compensation unit 231B may be provided before the dead zone gain unit 232 of the second embodiment shown in FIG. 16 (fourth embodiment). Also in this case, one of the two phase compensators 231 and 231B can be used mainly for target correction and the other can be used for noise removal or the like, so that a smoother feeling can be obtained.

1 Handle (steering wheel)
2 Column shaft (steering shaft, handle shaft)
10, 154 Torque sensor 12 Vehicle speed sensor 14 Rudder angle sensor 20, 150 Motor 30 Control unit (ECU)
130 Vehicle side ECU
140 EPS side ECU
141 Assist Control Unit 142 Switching Unit 200 Steering Angle Control Unit 210 Position Control Unit 220 Speed Control Unit 230 Target Steering Angle Correction Units 231, 231A, 231B Phase Compensation Unit 232 Dead Band Gain Unit 233 Limiter

Claims (11)

The manual steering control for driving the motor with the first motor current command value calculated based on at least the steering torque, and the second calculated by the rudder angle control unit so that the actual steering angle follows the target steering angle. In an electric power steering apparatus having a function of switching between automatic steering control for driving the motor according to a motor current command value,
A target steering angle correction unit that performs calculation processing according to a steering state and a vehicle speed for the steering torque, and outputs a target steering angle correction value;
A correction output unit that corrects the target steering angle with the target steering angle correction value and inputs the corrected target steering angle to the rudder angle control unit;
An electric power steering apparatus comprising: The target steering angle correction unit is
A phase compensator for compensating for the phase advance or phase lag based on the steering state of the steering torque;
The first compensation steering torque from the phase compensation unit is input, and there is a dead zone in a region where the first compensation steering torque is small, and the same method for increasing the first compensation steering torque according to the vehicle speed. A dead zone gain unit that outputs a second compensation steering torque that increases in the direction;
A limiter that limits the upper and lower limit values of the second compensation steering torque according to the vehicle speed and outputs the corrected target steering angle;
The electric power steering device according to claim 1, comprising: The electric power steering apparatus according to claim 2, wherein a second phase compensator is provided after the dead band gain unit. The target steering angle correction unit is
A dead zone gain unit that inputs the steering torque, and has a dead zone in a region where the steering torque is small, and outputs a first compensated steering torque that increases in the same direction as the method of increasing the steering torque according to the vehicle speed; ,
A phase compensator for compensating for phase advance or phase lag based on the steering state of the first compensation steering torque;
A limiter that limits the upper and lower limits of the second compensation steering torque from the phase compensation unit according to the vehicle speed, and outputs the corrected target steering angle;
The electric power steering device according to claim 1, comprising: The electric power steering apparatus according to claim 4, wherein a second phase compensation unit is provided upstream of the dead zone gain unit. The electric power steering apparatus according to any one of claims 2 to 5, wherein an output gain of the dead zone gain unit decreases as the vehicle speed increases. 6. The electric power steering apparatus according to claim 2, wherein a limit value of the limiter decreases as the vehicle speed increases. 6. The electric power steering apparatus according to claim 2, wherein the dead zone is variable according to the vehicle speed. The electric power steering apparatus according to any one of claims 1 to 8, wherein the steering state is an increase or a return of a steering wheel. The determination of the increase and the return of the rotation is performed by determining the relationship between the actual steering angle and the motor angular velocity, the relationship between the actual steering angle and the steering angular velocity, the relationship between the steering torque and the steering angular velocity, or the steering angular velocity and the Based on the relationship between the target steering angle and the deviation of the actual steering angle, or the relationship between the change rate of the target steering angle and the deviation of the steering angular velocity and the deviation of the target steering angle and the steering angle. The electric power steering device according to claim 9. The electric power steering apparatus according to claim 1, wherein the correction output unit is an addition unit.

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